The air whistled by them as the ship was drawn upward with ever-increasing speed. The other pa.s.sengers cowered in fright as the two men rolled over and over on the floor, banging at each other indiscriminately. Both were hurt. Karl's lip was split, and bleeding profusely. One eye was closing. But now he was on top and he pummeled his opponent to a pulp.

Long after he ceased resisting them, the blows continued until the features of Leon Lemaire were unrecognizable. The infuriated Karl did not see that one of the members of the party was creeping up on him from behind. Neither was he aware that the upward motion of the aero had ceased and that they now hung motionless in s.p.a.ce. A terrific blow at the base of his skull sent him sprawling. Must have been struck by a rocket, one of those funny ships that crossed the ocean so quickly. A million lights danced before his aching eyeb.a.l.l.s.

Lying p.r.o.ne across the inert body of his foe, dimly conscious and fingers clutching weakly, he knew that the cabin was filled with people.

Alien voices bellowed commands. There was the screaming of women; the sound of blows; curses ... then all was silence and darkness.

It was a far cry to the little book shop off Cooper Square, but Karl was calling for Rudolph when he next awoke to the realization that he was still in the land of the living. His head was bandaged and his tongue furry. A terrible hangover. Then he heard voices and they were discussing Peter Van Dorn. He opened one eye as an experiment. The other refused to open. But it might have been worse. At least he was alive; he could see well enough with the one good optic.

"Sh-h!" whispered one of the voices. "He's recovering!"

He looked solemnly into the eyes of an old man; a pair of wise and gentle eyes that reminded him somehow of Rudolph's.

"Quiet now, Peter," said the old man. "You'll be all right in a few minutes. Banged up a bit, you are, but nothing serious."

"Don't call me Peter," objected Karl. He loathed the sound of the name; loathed himself for his recent thoughts and actions. "I am Karl Kra.s.sin," he continued, "and as such will remain until I die."

There were others in the room and he saw glances of satisfaction pa.s.s between them. This was a strange situation. These men were not of the purple. Neither were they of the gray. Their garments shone with the whiteness of pure silver. And that's what they were; of finely woven metallic cloth. Was he in another world?

"Very well, Karl." The kind old man was speaking once more. "I merely want you to know that you are among friends--your father's friends."

Surprised into complete wakefulness, Karl struggled to a seated position and surveyed the group that faced him. They were a fine looking lot, mostly older men, but there was a refreshing wholesomeness about them.

"My father?" he faltered. "He's not alive."

"No, my poor boy. Derek Van Dorn left this life at the hands of your uncle, Zar Boris. But we, his friends, are here to avenge him and to restore to you his throne."

"But--but--I still do not understand."

"Of course not, because we've kept ourselves hidden from the world for more than twenty-two years, waiting for this very moment. There are forty-one of us, including Rudolph, my brother. We have lived in the jungle since Boris conquered the Eastern Hemisphere. But amongst our numbers were several scientists, two greater than was Boris, even in his heyday. They have done wonderful things and we are now prepared to take back what was taken from Derek--and more. His life we can not restore--Heaven rest him--but his kingdom we can. And to his son it shall be returned.

"You were given into Rudolph's care when little more than a babe in arms and he has cared for you well. We've watched, you know, in the detectoscopes--long range radiovision mechanisms that can penetrate solid walls, the earth itself, to bring to us the images and voices of persons who may be on the other side of the world. We've followed your every move, my boy, and the first time we feared for you was yesterday when the drug of the Zar's physician stole away your sense of right and wrong. But we were in time to save you, and now we are ready to kneel at your feet and proclaim you our king. First there is the Zar to be dealt with and then we shall set up the new regime. Are you with us?"

Karl gazed at the speaker in wonder. He a king? Always to live amongst the wearers of the purple? To be responsible for the welfare of half the world? It was unthinkable! But Zar Boris, the murderer of his own father--he must be punished, and at the hands of the son!

"I'll do it," he said simply. "That is, I'll do whatever you have planned in the way of exterminating the Zar. Then we'll talk of the new empire. But how is the Zar to be overcome? I thought he was invincible, with his Moon men and terrible weapons."

"Ah! That, my boy, is where our scientists have triumphed. True, his rays were terrible. They could not be combatted when he first returned.

The strange chemicals and gases of the Moon men defied a.n.a.lysis or duplication. His citadel atop the city of Dorn is proof against them all; proof against explosives and rays of all kinds known to him. The disintegration and decomposition rays have no effect on the crystal of its walls. It is hermetically sealed from the outer air so can not be ga.s.sed. The vibration impulses have no effect upon its reinforced structure. But there is a ray, a powerful destructive agent, against which it is not proof. And our scientists have developed this agency.

You shall have the privilege of pressing the release of the energy that destroys the arch-fiend in his lair. His dominance over, the empire will fall. We shall take it--for you."

A strange exaltation shone from the faces of those in the room, and Karl found that it was contagious. His bosom swelled and he itched to handle the controls of this wonderful ray.

"This ray," continued the brother of old Rudolph, "carries the longest vibrations ever measured, the vibrations of infra-red, the heat-ray. We have succeeded in concentrating a terrific amount of power in its production, and with it are able to produce temperatures in excess of that of the interior of the earth, where all substances are molten or gaseous. The Zar's crystal palace cannot withstand it for a second. He cannot escape!"

"How'll you know he's there at the time?" Karl was greatly excited, but he was curious too.

"Come with me, my boy. I'll show you." The old man led him from the room and the others followed respectfully.

They stopped at a circular port and Karl saw that they were high above the earth in a vessel that hovered motionless, quivering with what seemed like human eagerness to be off.

"This vessel?" he asked.

"It's a huge sphere; the base of our operations. To it we drew the aero on which you were fighting. A magnetic force discovered by our scientists and differing only slightly from that used in counteracting gravity. We let the rest of them go; foolishly I think. But it's done now and we have no fear. From this larger vessel we shall send forth smaller ones, armed with the heat-ray. The flagship of the fleet is to be yours and you'll lead the attack on Dorn. Here--I'll show you the Zar."

They had reached the room of the detectoscopes--a ma.s.s of mechanisms that reminded Karl of nothing so much as the vitals of the intermediate levels which he had visited with Leon--and Rhoda. He knew that he flushed when he thought of her. What a fool he had been!

A disc glowed as one of the silver-robed strangers manipulated the controls. The upper surface of Dorn swung into view. Rapidly the image drew nearer and they were looking at the crystal pyramid that was the Zar's palace. Down, down to its very tip they pa.s.sed. Karl recoiled from the image as it seemed they were falling to its glistening sides. The sensation pa.s.sed. They were through, penetrating solid crystal, masonry, steel and duralumin girders. Room after room was opened to their view.

It was magic--the magic of the upper levels.

Now they were in the throne room. A group of purple-clad men and women stood before the dais. Leon, Rhoda--all of his wild companions were there, facing the dais. The Zar was raging and the words of his speech came raucously to their ears through the sound-producing mechanism.

"You've failed miserably, all of you," he screamed. "He's gotten away and you know the penalty. Taru--the vibrating ray!"

The Moon man already was fussing with a gleaming machine, a machine with bristling appendages having metallic spheres on their ends, a machine in which dozens of vacuum tubes glowed suddenly.

Rhoda screamed. It was a familiar sound to Karl. He noted with satisfaction that Leon could hardly stand on his feet and that his face was covered with plasters. Then, startled, he saw that Leon was shivering as with the ague. His outline on the screen grew dim and indistinct as the rate of vibration increased. Then the body bloated and became misty. He could see through it. The vibrating death! His father had gone the same way!

Karl groaned at the thought. The whine of the distant machine rose in pitch until it pa.s.sed the limit of audibility. Tiny pin-points of incandescence glowed here and there from the Zar's victims as periods of vibration were reached that coincided with the natural periods of certain of the molecules of their structure. They were no longer recognizable as human beings. Shimmering auras surrounded them. Suddenly they were torches of cold fire, weaving, oscillating with inconceivable rapidity. Then they were gone; vanished utterly.

The Zar laughed--that horrible cackle again.

"Great G.o.d!" exclaimed Karl, "let's go! The fiend must not live a moment longer than necessary. Are you ready?"

Rudolph's brother smiled. "We're ready Karl," he said.

The great vessel hummed with activity. The five torpedo-shaped aeros of the battle fleet were ready to take off from the cavities in the hull.

In the flagship Karl was stationed at the control of the heat-ray. His instructions in its operation had been simple. A telescopic sight with crosshairs for the centering of the object to be attacked; a small lever. That was all. He burned with impatience.

Then they were dropping; falling clear of the mother ship. The pilot pressed a b.u.t.ton and the electronic motors started. A burst of roaring energy streamed from the tapered stern of their vessel and the earth lurched violently to meet them. Down, down they dived until the rocking surface of Dorn was just beneath them. Then they flattened out and circled the vast upper surface. From the corner of his eye Karl saw that the other four vessels of his fleet were just behind. There was a flurry among the wasplike clouds of pleasure craft over the city. They scurried for cover. Something was amiss!

"Hurry!" shouted Karl. "The warning is out! There is no time to lose!"

He pressed his face to the eye-piece of his sight, his finger on the release lever of the ray. The crystal pyramid crossed his view and was gone. Again it crossed, more slowly this time. And now his sight was dead on it, the gleaming wall rushing toward him. Pressure on the tiny b.u.t.ton. They'd crash into the palace in another second! But no, a brilliant flash obscured his vision, a blinding light that made the sun seem dark by comparison. They roared on and upward. He took his eye from the telescope and stared ahead, down. The city was dropping away, and, where the crystal palace had stood, there was a spreading blob of molten material from which searing vapors were drifting. The roofs of the city were sagging all around and great streams of the sparkling, sputtering liquid dripped into the openings that suddenly appeared. Derek Van Dorn was avenged.

"Destroy! Destroy!" yelled Karl madly. A microphone hung before him and his words rang through every vessel of his convoy.